Process of refining vegetable oils



Feb. 4, 1941. Q FRfiplNs' 2,230,796

PROCESS OF REFINING VEGETABLE OILS Filed April 22, 1938' Patented F ch. 4, 1941 ATENT OFFIQE PROCESS OF REFKNING VEGETABLE OILS Application April 22, 1938, Serial No. 203,548 In Sweden June 25, 1937 13 Claims.

In the refining of cottonseed oil and other vegetable oils it is known to flow the oil and an alkali, such as caustic soda, into a mixer, or into a pre-mixer if a subsequent mixer is employed, either in separate streams or in a single stream immediately after the alkali is added to the oil; the mixing, whether it be practiced in one or two stages, eifecting a saponification of the fatty acids. The mixture then goes to a centrifuge wherein the oil is separated from the soaps. The oil is usually heated prior to mixing, but my invention is not concerned with temperature control but relates to the mixing or pre-mixing step. It is preferable to flow the oil and alkali into the mixer or pre-mixer in separate streams, and it is obviously advantageous, at whatever point the alkali is added to the oil, to inject it into the oil in the form of a stream so fine that it tends to break into more or less fine drops to thereby provide a large surface area of contact between the oil and the alkali. However, this method of mixing is of limited efficiency if, as in the prior art, the mixing or pro-mixing takes place in a long horizontal container through which the mass of oil moves comparatively slowly, since in such mixers the comparatively slow moving oil stream itself has little or no effect in comminuting the alkali and by no means maximum contact surface between the oil and alkali is secured. Moreover, in such a mixer the soap deposits and accumulates on the walls of the tube.

In my invention the alkali is fed to a mixer or premixer under constant pressure out of a small orifice or orifices into a mass of oil which is in rapid motion, preferably that imparted toit by rapid rotation around a vertical axis. The velocity of the oil, at the point or points of admission of the alkali thereto, should not be less than feet per second and may be as high as 100 feet per second. The diameter of the discharge orifice for the alkali should be between .1 mm and mm. The desirable proportions of oil and alkali will vary with the oil to be refined and need not vary from the known practice, although, in my process, a smaller proportion than usual of alkali is permissible. As an example, the oil may flow through the mixing chamber at the rate of 1000 gallons per hour and the alkali may flow through the mixing chamber at the rate of 50 gallons per hour. The oil in the mixer must not only be in rapid movementbut it should also be maintained in a turbulent condition. The rate of inflow of the alkali and the speed of rotation of the oil being predetermined and constant factors, it is insured that successive increments of alkali are, by the combination of these factors, separated not only in drops as fine as may be desired, but also into drops of uniform size. The size of the drops may be decreased by reducing the size of the discharge orifice in the alkali feed tube and also by increasing the speed of the oil.

In the drawing:

Fig. 1 is a diagram, in sectional elevation, of a mixer adapted to practice my improved process. Fig. 2 is a plan View of the mixer of Fig. 1. Fig. 3 is a view, similar to Fig. 1, of a modification.

Referring to Fig. 1: The oil is admitted, through a feed pipe I0, into a mixing chamber H in which is centrally positioned a rotating spindle l2 carrying wings l3 which impart to the oil a rapid movement of rotation. The alkali is supplied under constant pressure'through a tube l4 tapered at the end to provide a small discharge orifice. Preferably the mixing chamber is an uprightcylinder in which the wings rotate on a vertical axis. Deposit of soap on the walls of the mixer is practically impossible. The outlet i5 from the mixer is arranged at the bottom thereof. The reaction is quick and complete. The size of the drops into which the alkali is separated may be varied by varying the size of the outlet orifice in the alkali feed tube I4 or by varying the speed of rotation of the wings. As an example, the mixing chamber may at any given time hold about 20 gallons, and the wings may revolve at the rate of 1000 R. P. M.

In Fig. 3 the mixer is a centrifugal pump 20. The oil is supplied through the tube 2i and the alkali through the tube 22, which is provided with a number of outlets 23 opening into the pump housing at different distance from the axis of rotation of the pump. As the velocity of the oil at the point of contact with the incoming alkali varies with the distance from the center of such point of contact, and since the size of the alkali drops is a function of this velocity, the size of the drops may be varied and predetermined by using different outlets 23. As an example, the pump may have a capacity of about 2000 gallons per hour and its speed may be about 3000 R. P. M.

What I claim and desire to protect by Letters Patent is:

1. In the process of refining vegetable oil by mixing a flowing stream of the same with an alkali to effect saponification of the fatty acids, followed by separation of the soaps and oil, the

step of effecting the mixing by imparting to the oil, in its travel through one zone of the traveling oil stream, a movement of rapid rotation, and injecting into said zone under pressure a fine stream of the alkali, and regulating the size of the drops into which the alkali is thereby separated by varying the distance from the center of rotation of the oil at which the alkali contacts with the oil.

2. In the process of refining vegetable oil by mixing a continuously flowing stream of the same with an alkali to effect saponification of the fatty acids, followed by separation of the soaps and oil, the step of effecting the mixing by imparting to the oil, in its travel through one zone of the traveling oil stream, a movement of such rapid rotation that it will be maintained in a turbulent condition and that the bulk of it will be maintained at a speed of not less than ten feet per second, and continuously injecting into that part of the body of oil which is rotating at that speed a stream of the alkali so fine that, at such specified speed of the oil, the alkali is separated into drops so fine and of such substantially uniform size as to insure a maximum contact and reac tion between the oil and the alkali.

3. In the process of refining vegetable oil by mixing a continuously flowing stream of the same with an alkali to effect saponification of the fatty acids, followed by separation of the soaps and oil, the step of efiecting the mixing by imparting to the oil, in its travel through one zone of the traveling oil stream, a movement of such rapid rotation that it will be maintained in a turbulent condition and that the bulk of it will be maintained at a speed of not less than ten feet per second, and adding alkali to the oil by continuously injecting substantially all such alkali into the body of oil at the inlet end of said J zone which is rotating at that speed in the form of .a stream so fine that, at such specified speed of the oil, the alkali is separated into drops so fine and of such uniform size as to insure a maximum contact and reaction between the oil and the alkali.

4. In the process of refining vegetable oil by mixing a continuously flowing stream of the same with an alkali to effect saponification of the fatty acids, followed by separation of the soaps and oil, the step of efiecting the mixing by imparting to the oil, in its travel through one zone of the traveling oil stream, a movement of such rapid rotation that it will be maintained in a turbulent condition and that the bulk of it will be maintained at a speed of not less than ten feet per second, and adding alkali to the oil by continuously so injecting the alkali in the form of a fine stream into that part of the body of oil which is rotating at that speed that substantially all the alkali, during the travel of the oil through said zone, will have substantially the same time of contact and reaction with the oil, thereby insuring substantially maximum and uniform contact and reaction between the oil and the alkali.

5. In the process of refining vegetable oil by mixing a continuously flowing stream of the same with an alkali to efiect saponification of the fatty acids, followed by separation of the soaps and oil, the step of effecting the mixing by imparting to the oil, in its travel through one zone of the traveling oil stream, a movement of such rapid rotation that it will be maintained in a turbulent condition and that the bulk of it will be maintained at a speed of not less than ten feet per second, and adding alkali to the oil by continuously injecting the alkali in the form of a fine stream into the oil at only approximately the peripheral and most rapidly rotating part of the rapidly rotating body of oil to thereby efiect the separation of the alkali into drops so fine and of such substantially uniform size as to insure a maximum contact and reaction between the oil and the alkali.

6. The process defined in claim 2 which comprises also regulating the size of the drops by regulating the fineness of the supplied stream of the alkali.

7. The process defined in claim 2 which comprises also regulating the size of the drops by regulably varying the speed of rotation of the oil, at the point of injection of the alkali into the oil, above the minimum speed specified.

8. The process defined in claim 3 which comprises also regulating the size of the drops by regulating the fineness of the supplied stream of the alkali.

9. The process defined in claim 3 which comprises also regulating the size of the drops by regulably varying the speed of rotation of the oil, at the point of injection of the alkali into the oil, above the minimum speed specified.

10. The process defined in claim 4 which comprises also regulating the size of the drops by regulating the fineness of the supplied stream of the alkali.

11. The process defined in claim 4 which comprises also regulating the size of the drops by regulably varying the speed of rotation of the oil, at the point of injection of the alkali into the oii, above the minimum speed specified.

12. The process defined in claim 5 which comprises also regulating the size of the drops by regulating the fineness of the supplied stream of the alkali.

13. The process defined in claim 5 which comprises also regulating the size of the drops by regulably varying the speed of rotation of the oil, at the point of injection of the alkali into the oil, above the minimum speed specified.

OLOF EINAR FRoDING. 

